$cos(2\phi_h)$ asymmetry in $J/\psi$ production in unpolarized $ep$ collision in NRQCD

Abstract

We present a recent calculation of the transverse momentum dependent gluon distributions inside unpolarised protons and show how the ratio of the linearly polarized and the unpolarized gluon distribution in the proton can be probed by looking at $Cos(2\phi_h)$ asymmetry in $J/\psi$ production in unpolarized $ep$ collision. We use NRQCD for estimating $J/\psi$ production and include contributions both from color singlet and color octet states.